This invention relates generally to wind power machines and, more particularly, to wind turbines.
Efforts to develop efficient wind turbines for converting wind energy into electrical energy have increased dramatically. Generally, a wind turbine includes a rotor assembly mounted for rotation about either a horizontal or vertical axis, a turbine shaft coupled to the rotor assembly and an electric generator or alternator driven by the shaft to generate electric power.
Conventional wind turbines are often provided with certain features in order to improve efficiency. For example, a wind vane may be provided for turning a horizontal axis rotor assembly into the wind in the case where wind direction changes during operation. A wind deflector may be provided upwind of a vertical axis rotor assembly in order to direct the wind current into the wind-receiving elements of the rotor assembly. In this connection reference is made to U.S. Pat. No. 3,970,409 which discloses a vertical axis wind turbine which includes a rudder connected to a wind deflector by an arm which is pivotally mounted to the turbine shaft so that the wind deflector position is automatically adjusted upon changes in wind direction to provide maximum effectiveness.
One problem for which a solution has not as yet been found is to constantly maximize efficiency of a wind turbine for all working wind velocities. In the case of horizontal axis wind turbines, rotor rotation has been controlled by turning the rotor blades gradually into and out of the wind or tilting the blades forward and rearward or turning the blades edgewise into the wind and back. Another problem is to prevent damage to the wind turbine when unusually high wind velocities occur, such as during hurricanes or squalls. For example, if the turbine rotates too fast under high wind conditions, stress and fatigue can damage the rotor assembly, drive shaft, and gear box, or burn out the generator. These problems have not been satisfactorily solved.